This invention relates to ink jet printheads. More particularly, this invention relates to an ink jet printhead that incorporates closure mechanisms.
The Applicant has invented an ink jet printhead that is capable of generating text and images at a resolution of up to 1600 dpi.
In order to achieve this, the Applicant has made extensive use of micro electro-mechanical systems technology. In particular, the Applicant has developed integrated circuit fabrication techniques suitable for the manufacture of such printheads. The Applicant has filed a large number of patent applications in this field, many of which have now been allowed.
The printheads developed by the Applicant can include up to 84000 nozzle arrangements. Each nozzle arrangement has at least one moving component that serves to eject ink from a nozzle chamber. The components usually either act directly on the ink or act on a closure which serves to permit or inhibit the ejection of ink from the nozzle chamber.
The moving components within the printheads are microscopically dimensioned. This is necessary, given the large number of nozzle arrangements per printhead. The Applicant has spent a substantial amount of time and effort developing configurations for such printheads.
One of the reasons for this is that, as is known in the field of integrated circuit fabrication, cost of on-chip real estate is extremely high. Furthermore, it is important that levels of complexity are kept to a minimum since these significantly increase the cost of fabrication.
Integrated circuit fabrication techniques involve what is generally a deposition and etching process. As a result, devices which are manufactured in accordance with such techniques are usually, of necessity, in a layered construction. Furthermore, it is important to develop a configuration where a high number of devices can be fabricated per unit area of chip surface.
A problem associated with such a high number of nozzle arrangements is that ink must be selectively physically ejected from each of the nozzle arrangements. This can result in excessive expenditure of energy. Furthermore, the requirement of having an ink mover in each nozzle chamber can result in a printhead with an unacceptably high level of complexity. Applicant has conceived the present invention in order to address this issue.
According to a first aspect of the invention there is provided an ink jet printhead that is manufactured in accordance with an integrated circuit fabrication technique, the ink jet printhead comprising:
a substrate; and
a plurality of nozzle arrangements positioned on the substrate, each nozzle arrangement comprising:
nozzle chamber walls that define a nozzle chamber having an inlet for fluid communication with a pulsed ink supply; and
a closure mechanism that is positioned on the substrate and is operable between a closed condition in which the closure mechanism serves to close the inlet and an open condition in which ink is permitted to pass into the nozzle chamber.
According to a second aspect of the invention, there is provided an ink jet printhead that comprises
a substrate;
an ink reservoir arranged on the substrate;
a plurality of nozzle arrangements positioned on the substrate, each nozzle arrangement comprising nozzle chamber walls that define a nozzle chamber having an inlet that is in fluid communication with the ink reservoir and a closure mechanism that is positioned on the substrate and is operable between a closed condition in which the closure mechanism serves to close the inlet and an open condition in which ink is permitted to pass into the nozzle chamber; and
a pressurizing mechanism that is operatively arranged with respect to the ink reservoir, the pressurizing mechanism being configured to pressurize ink within the reservoir in a pulsed manner to generate pressure pulses to eject ink from the nozzle chambers on operation of the pressurizing mechanism, when the closure mechanisms are in the open condition.
According to a third aspect of the invention, there is provided a method of printing with an ink jet printhead having a substrate, a plurality of nozzle arrangements positioned on the substrate, each nozzle arrangement having nozzle chamber walls that define a nozzle chamber having an inlet, a closure mechanism that is positioned on the substrate and that is operable between a closed condition in which the closure mechanism serves to close the inlet and an open condition in which ink is permitted to pass into the nozzle chamber, the method comprising the steps of:
applying pressure pulses to ink supplied to each nozzle arrangement; and
activating closure mechanisms of selected nozzle arrangements while applying such pressure pulses, so that the closure mechanisms are moved into their open conditions permitting ink to be ejected from the nozzle chambers of the selected nozzle arrangements.